Field of the Invention
The present invention relates to an ink, an ink cartridge having such an ink, and an inkjet recording method using such an ink.
Description of the Related Art
In recent years, inkjet recording apparatuses have had increased opportunities to be used in business fields with enhancement of their image quality and recording speed. Performances required for the ink for inkjet used in the business field include reliability of the ink (discharge stability and the like), the image quality (high image density, feathering resistance and the like), and fastness of images (abrasion resistance, highlighter resistance, water resistance and the like). Among these performances, the inks using a self-dispersing pigment rather than a polymer-dispersing pigment to enhance an optical density of an image and further containing a polyurethane polymer to enhance the highlighter resistance on the image have been studied [Japanese Patent Application Laid-Open (Translation of PCT Application) No. 2005-515289]. In Japanese Patent Application Laid-Open No. 2005-515289, it is described that the highlighter resistance on the image is improved by an aqueous inkjet ink containing the polyurethane polymer having an acid group and the self-dispersing pigment.